William c



W. C. CORYELL.

ENDLESS BELT.

APPLICATION FILED OCT. 24, 1918.

1 09,245, Patented July 8, 1919.

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iNvENTo WILLIAM G. CORYELL, OF WASHINGTON, DISTRICT OF COLUMBIA.

ENDLESS BELT.

Specification of Letters Patent.

Patented July 8, 1919.

Original application filed July 6, 1917, Serial No. 178,924. Divided and this application filed October 24,

To all whom it may concern:

Be it known that I, WILLIAM C. CORYELL, a citizen of the United States, residing at lVashington, District of Columbia, have invented certain new and useful Improvements in Endless Belts, of which the following is a specification.

The present invention relates to continuous metal belts and the principal object of the invention is to produce an efficient, powerful, smooth-running, high-speed, powert-ransmitting belt.

The present application is a division of my prior application, Serial No. 17 8924:, filedJuly 6, 1917.

Briefly stated, I produce an endless belt out of a seamless ring of steel or other suitable metal, by expanding the ring by rolling, hammering, or pressing, thereby increasing its length and reducing its thickness. Generally, the roughing work will be done while the metal is hot, and the finishing work while the metal is at a lower temperature, or when it is cold. The cold working permits of more exactness in the finished belt and produces a better quality of steel and a better surface. Finally I trim the edges of the belt, preferably in a trimmer, and round off the edges by grinding or filing, and thus obtain a smooth edge. After grinding, the edges may be more highly finished by polishing. In some instances one or both surfaces of the belt maybe ground off or otherwise dressed to a desired thicknes. The belt resulting from this process has a very high yield point which approaches closely the ultimate strength. Up to this yield point the belt is truly elastic. It is also practically free from elongation under high working stresses. It possesses other advantageous qualities which will appear more fully hereinafter.

The accompanying drawing'will assist in following the process of making the belt and illustrating its characteristics. The scope of the invention will be particularly pointed out in the appended claims.

In said drawing Figure 1 is a diagrammatic view of a blank metal ring in position between the reducing elements of a reducing machine, such as the rolls of an endless Serial No. 259,548.

belt mill; Fig. 2 is a similar view showing the ring somewhat enlarged; Fig. 3 is a somewhat similar view illustrating the loop of metal at the conclusion of the h0t'work mg operation; Fig. 4 is a view representing the cold rolling operation; Fig. 5 is a sectional view, considerably enlarged, illustratmg the trimmed and rounded edges of a belt; Fig. 6 is a perspective view of a completed belt; Fig. 7 is a transverse section, on an enlarged scale, of the loop as it ap-' pears immediately following the cold rolling operation and illustrating, by dotted lines, portions that may be cut away by grinding; Figs. 8 and 9 are diagrams illustrating the deformation of the metal as it passes through the rolls; Fig. 8 being a plan view and Fig. 9 a vertical section of the metal in engagement with the rolls. Throughout these views like characters refer "to like parts.

Referring to the drawing in detail, 10 designates the ring of metal from which the finished belt is to be produced. The ring may be produced in various ways. Thus it may consist of a short section of seamless steel pipe or tube. Again it may consist of a block of metal which is perforated and turned down so as to form a ring. In other instances, it may be a ring punched out of a plate. I refer the section of a seamless tube, because if the ingot. from which the tube is made, contained blowholes or segregation, the defects are more certain of being eliminated than when plates, welded tubes, or welded rings are used. The operation of expanding the ring 10 is performed principally by hot rolling, or by hot hammering or pressing between cylindrical surfaces. The ring is first heated and then reduced by the reducing elements of a reducing machine, such as the rolls of an endless belt mill, the hammer and anvil, a hammering machine, or the jaws of a press or squeezing machine. In the present disclosure the 'ring is shown threaded upon or slipped over the roll of a belt mill of the kind illustrated in my application Serial No. 59,582, filed November 4:, 1915and patented July 17, 1917, as Patent No. 1233647.

The reducing elements are the rolls 11 and 12. As these are operated, the length of the loop 10 is increased, its thickness is decreased, and its width is increased very slightly. These three deformations are called, respectively, elongation, reduction and spread, and are expressed numerically in percentage of the original dimension. When the elongation and reduction have proceeded until the loop becomes unwieldy, the loop maybe drawn out by hand or by any suitable device, such as the pulley 13. When the loop 10 has been expanded by the hot working operation to a little less than its desired length, the hot working is discontinued and the elongated loop is allowed to cool. It is then threaded upon or slipped over aro l of the finishing mill, which is preferably of the type shown in my Patent No. 1,221,029, granted April 3, 1917. In this mill it is cold rolled between the rolls 11 and 12' which cooperate with roll 12". This cold rolling gives the steel a permanent set, greatly raises its yield point and permits of most exact rolling as to length, thickness and surface finish.

The amount of cold rolling will vary with the metal used. Thus some steel will take upward of twenty-five per cent. elongation between annealings, while other steel will not elongate more than ten per cent. without showing signs of being overworked. The

annealing and also the proportion of carbon, nickel and other alloying elements each have their effects.

The effect of overworking the metal in rolling or hammerin 'or squeezing, first appears at the edges 0 the band. This is because of the more severe working of the metal at this point than elsewhere across the section. The spread between the rolls is much less in actual displacement than is the reduction in thickness. The elongation is almost exactly inversely proportional to the reduction. Figs. 8 and 9 exaggerate the spread so as to make the action between the rolls more clearly understood. However, the working of the metal is more severe at the edges than elsewhere and consequently the edge is the location of the first breaking down of the metal due to overwork. This action will be apparent from a consideration of the diagrams of Figs. 8 and 9. In these figures the metal is shown passing between the rolls 11 and 12. A similar action will occur where hammering or other equivalent reducing means are employed. In these diagrams the distances between the longitudinal lines 17 and the distances between the transverse lines 18 illustrate respectively the relative lateral and longitudinal displacements of particles of metal before reaching the rolls, while passing between them, and after leaving them. From the position of these indicat- I ing lines it will be seen that the metal has a slight bulge in breadth and thickness, as indicated at. 19 and 20, due to the squeezing of the metal by the rolls as the piece is entering. As these lines clearly show, the piece, while passing between the rolls, gradually decreases in thickness in conformity to the curvature of the rolls, as indicated by 21, and gradually increases in width, as indicated at 22. It will be seen that the center or axial line 17 has no distortion. Departing from that line and moving toward the edges, lateral distortion takes place and gradually increases to a maximum at the outer edges. Likewise, in moving toward the top and bottom from the center or axial line 17, vertical distortion begins and increases to a maximum at the top and bottom surfaces. The distortion at these latter surfaces, however, is less than that at the edges. From these considerations, it is clear that the working of the metal is more severe at the edges of the strip than elsewhere. I

Because the edge is more severely worked than the mid-portion of the band, it is desirable to trim ofi' a small portion of the are thus removed.

The trimmer does not leave a true and uniform edge, so the belt is put through an operation of having the edges rounded. This may be done with abrasive wheels or with files. The edges are thus made smooth and uniform and straight. There is also less danger of the edge cutting any object which it may rub against. However, in good present practicev all exposed belts, whatever the material, are protected by inclosures.

The dressing of the edges is an important and necessary step in the manufacture of the belt. 'It leaves the edges free of the tiny ragged edge or other defects left by the shears. All fractures, even microscopic ones, are to be avoided. Grinding the edges removes these. If left in the belt, the tiniest of fractures would develop into a large one, which in time would ruin the belt. If the abrasive wheel or stone be rough, then I thickness and configuration to the transverse section of the belt. Furthermore, it may be annealed from time to time. \Vhether the annealing is done or not Will depend largely upon the conditions existing in any particular case. In some instances it may be desirable to pickle the ring because of the scale being formed during annealing. Or, after cold rolling, the belt may be pickled so as to cleanse it for a nickelplating or other metal coating process. The edge of the belt may be dressed several times during the complete course of its manufacture, and the surface may also be repeatedly dressed. The belt may also be subjected to heat treating and tempering.

The belt which I have produced has many advantages over belts of the prior art. Thus it may be used with one pulley, or three pulley belt tighteners, which require short turns and an engagement of one side of the belt at one point and of the other side at another point. The belt which I have produced, because of its high tensile strength, elasticity and permanent non-elongation under high working stresses, can also be. used in making a very short drive. It would not be practicable to use leather belts or rope drives in this way. It has been common practice heretofore, when such short drives were required, to use toothed gearing. Because of the great tensile strength and the unyielding elastic property of my belt, it is also capable of use in vertical drives, that is, in drives where one pulley is directly above the other. Ordinary belting, due to its yielding character, de pends upon its weight on the pulley for its adhesion and therefore cannot be used in a vertical drive for it does not rest or lay on the lower pulley. Also my belt has no practical limit of speed since it can safely run as fast as the bursting speed of the fast est pulley. Then, my belt runs extremely smooth, without jar, vibration or appreciable slip. My belt is not affected expansively by moisture and consequently is independent of wet and dry atmosphere.

Although I have frequently referred to steel as the metal for producing the belt, I may under certain conditions use phosphor bronze or other alloys of high tensile strength, high yield point and-high modulus of elasticity. In general, in the manufacture of my belt, I prefer a metal having a. high yield point or elastic limit, such as rolled or hammered carbon steel, nickel steel, or other alloy steels. This elastic limit is far beyond that of all present belt-materials. For example, I may employ steel having an elastic limit of 160,000 pounds or. more per square inch of section and an ultimate strength of 180,000 pounds or more per square inch. The elastic limit of belting in use at present is so loW and variable as to be 'in(leterminatc. Consequently it is continually yielding under ordinary working loads. The ultimate strength of leather is about 3.000 pounds per square inch of section. lVith a factor of six for each material, the steel belt-s may be worked at 30,000 pounds tension per square inch of section. while the leather may be worked at 500 pounds per square inch of section. Under these conditions, with the modulus of elasticity of steel at 30,000,000 and of leather at 12,400, the steel will stretch about 0.10 inches per 100 incl'ies of length and the leather will stretch about 4.0 inches per 100 inches of length. In other words, a strip of steel 83.0 feet long subjected to a pull of 80,000 pounds per square inch will elongate 1 inch, while leather 2.06 feet long subjected to a pull of 500 pounds per square inch of sec tion will elongate 1 inch. Relatively then, leather, when stressed to one-sixth of its ultimate strength, will stretch about 40.0 times as far as steel when stressed to one-sixth of its ultimate strength. Furthermore, when the loads are removed the steel returns absolutely to its original length, while the leather does not. The working strength of steel is 60 times greater than that of leather per square inch of section, and about 4 times greater. when compared per inch of Width. Thus my belt is practically free from permanent elongation at high working stresses and is truly elastic, returning to its exact original dimension when the load is removed, while a leather belt stretches-while in use and is left elongated after use. In other Words, leather yields under ordinary Working stresses, and steel does not yield at all under severe working stresses.

It should be borne in mind that while some present belt materials have less elongation under stress than leather, their ulti mate strength is also less, so that in referring to leather as I have done above, I intended to select the most representative belting material.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A thin flat jointless metal power-trans mitting belt of the same cross sectional con figuration throughout having a high yield point closely approaching its ultimate strength and being truly elastic and practically free at all points in its cross-section from permanent elongation under highworking stresses.

2. A thin fiat jointless metal power-transmitting belt of the same cross sectional configuration throughout having a high yield point closely approaching its ultimate strength and being truly elastic and practically free from elongation under high working stresses, and having smooth dressed edges free from incipient cracks and other defects.

3. A thin flat jointless metal power-transmitting belt of the same cross sectional eonfiguration throughout having a high yield point closely approaching its ultimate strength and being truly elastic and practically free from permanent elongation under high Working stresses and having dressed surfaces and smoothly dressed edges free from incipient cracks and other defects.

In testimony whereof I have hereunto 10 subscribecl-my name this 24th day of Octoher, A. D. 1918.

WILLIAM C. CORYELL. 

